Seth Woolley's Man Viewer

ACOS(3)                    Linux Programmer's Manual                   ACOS(3)



NAME
       acos, acosf, acosl - arc cosine function

SYNOPSIS
       #include <math.h>

       double acos(double x);
       float acosf(float x);
       long double acosl(long double x);

       Link with -lm.

DESCRIPTION
       The  acos()  function calculates the arc cosine of x; that is the value
       whose cosine is x.  If x falls outside the range -1 to 1, acos()  fails
       and errno is set.

RETURN VALUE
       The  acos() function returns the arc cosine in(1,8) radians and the value is
       mathematically defined to be between 0 and PI (inclusive).

ERRORS
       EDOM   x is out of range.

CONFORMING TO
       SVID 3, POSIX, BSD 4.3, ISO 9899.  The float and long  double  variants
       are C99 requirements.

SEE ALSO
       asin(3), atan(3), atan2(3), cos(3), sin(3), tan(3)



                                  2004-10-06                           ACOS(3)